The present invention relates to ground fault interrupters which are sensitive to low resistance faults occurring between neutral conductors in an A.C. distribution circuit and ground.
National and local code standards require that ground fault interrupters used to protect grounded neutral, two and three wire A.C. distribution circuits function to interrupt the supply of power to such distribution circuit on .[.occurence.]. .Iadd.occurrence .Iaddend.of a low resistive ground fault between any electrified or neutral line and ground. All prior systems used for detecting the presence of a fault between ground and a neutral line have employed circuits which are continuously energized. These have taken the form of circuits energized by transformer or inductive windings connected between the distribution lines, or by circuits that require active high frequency superimposed voltages that are interrupted or otherwise attenuated when such ground faults occur. Such circuits are subject to influence by transient currents, and in the case of high frequency superimposed voltages the entire distribution system is subjected to these signals which may be highly objectionable in some instances.